Automatic control for humidifiers



Jan. 12, 1937. F. BULLOCK I AUTOMATIC CONTROL FOR HUMIDIFIERS Filed Nov.22, 1934 w www mw 6 mm w v? N m A m O 6 4O 50 PERCENT HUM/O/TY ATTORNEYPatented Jan. 12, 1937 AUTOMATIC CONTROL FOR HUIVIIDIFIERS FrankBullock, Lake Geneva, Wis assignor to Middlebury Electric ClockCorporation, a corporation of Illinois Application November 22, 1934,Serial No. 754,383

1 Claim.

This invention relates to improvements in automatic control forhumidifiers and more particularly to an automatically operated controlswitch for connecting and disconnecting an electrically operatedhumidifier upon a decrease or increase in the proper degree of moisturein the air for any given temperature.

Various types of air humidifiers have been offered for sale from time totime wherein small electric motors are provided to drive a fan and watervaporizing impellor. Such devices are intended to be connected with thehouse lighting circuit and a manual control switch is usually providedso that the user may operate the humidifier at will whenever it is foundthat the surrounding air has become too dry. This procedure, however,necessitates reference to a thermometer and hygrostat and bothersomemanual effort.

It is, therefore, an object of my invention to provide an improvedautomatic control for electrically operated humidifiers which willautomatically turn on and oif the humidifier as the relative humidity ofthe air changes thereby to maintain at all times a proper relativehumidity for the particular room temperature.

Another object is to provide an automatic control for humidifiers, asdescribed, incorporating mechanism sensitive to the temperature changesin the air for compensating the functioning of the humidity responsiveswitch control mechanism thereby to cause the control switch to remainopen under temperature and humidity proportions which if plotted upon agraph, one proportion against the other, would result in an irregularcurve. This feature of my invention I consider of great importance sinceat higher than normal temperatures humidity must be increased above thatprescribed as within the ideal comfort zone in order to prevent thedrying of furniture and similar articles in the room.

Other objects, the advantages, and uses of my invention will be apparentafter reading the following specification and claim and afterconsideration of the drawing forming a part of the specification,wherein:

Fig. 1 is a top plan view of an automatic humidifier control deviceconstructed in accordance with my invention;

Fig. 2 is a view of the device of Fig. 1 with the cover and dialsremoved;

Fig. 3 is a sectional view along the line 3-3 of Fig. 1;

Fig. 4 is a sectional view along the line 4-4 of Fig. 2; and

Fig. 5 is a chart representing a temperature and humidity curve such asthat which may be maintained through the use of my improved controldevice.

With reference to the drawing the control device may comprise a basemember 2 of moulded composition, having a pair of spaced apart upstanding supports 3 formed therein. A steel shaft 4 extending betweenthe supports 3 and fixed thereto by set screws 5 serves as a mountingfor the temperature and humidity responsive elements of the device.

The temperature responsive element may comprise a disc 6 of mouldedcomposition rotatably mounted uporrthe shaft 4 through the medium of asleeve 1 extending centrally through the disc and a spiral of bimetal 8,the inner end of which is fixed to a sleeve 9 secured to the shaft 4 bya set screw II and the outer end of which is secured to the disc 6through the medium of a pin l2.

The humidity responsive element may be of similar construction,including a disc l3, sleeve It, a spiral of hygroscopic material I5secured to a sleeve l6 at its inner end, a sleeve set screw l1 and a pinl8 rigidly connecting the outer end of the spiral with the disc I3. Thespiral of hydroscopic material may be constructed of a thin brass striphaving cemented to one side thereof a strip of paper subject toshrinkage and stretching in accordance to decreases and increases inrelative humidity respectively or, if desired, a strip of cat-gut may besubstituted for the paper.

Resilient metal contact fingers 2| and 22 are located between theopposed faces of the discs 6 and I3 in spaced apart parallelrelationship, as shown in Fig. 2 and are secured, at their ends, to thebase 2 by screws 23. Each of the fingers has a contact member 24 oftungsten or other suitable contact metal at its outer end, which contactmembers are normally held apart from one another by the tendency of thecontact fingers to lie apart from one another.

Cams 25 and 26 are formed on the opposed faces of the discs 6 and I3respectively and each has a form determined by the dotted curve 21plotted in the chart of Fig. 5 representing proper or desirablerelationship between temperature and humidity of air for humanoccupancy. The cams are so located upon the discs 6 and I3 as toregister with the contact fingers 2| and 22 respectively and tocooperate with one another and with the contact fingers to cause thecontact members 24 to contact with one another under all temperature andrelative humidity conditions represented in the chart oi Fig. 5 whichlie beneath the dotted curve 21. Since the curve 21 is other than astraight line. the suri'aces of thecamsllandflwillbeirregularincontourasbest illustrated in Fig. 2.

In order that a person may determine the temperature and relativehumidity at a glance for the surrounding air dials II and 32 calibratedin temperature in degrees Fahrenheit and percent humidity are secured tothe discs 0 and i8 and may be viewed through windows it in the cover llof the device, I prefer to form the cover 34 with a plurality ofopenings ll therethrough for admitting air to the elements I and I 5.

In operation my improved automatic control device is placed in anyposition within a room where control may best be carried out, such asupon the wall, or, it desired, upon the humidifier device. 'flre binderscrews 23 may be connected in series. as by wires 30, with theelectrical control circuit of the electrical humidifier so that when thecontacts 24 touch one another the humidiner will operate.

It is to be understood that the above described embodiments oi myinvention are for the purpose of illustration only and various changesmay be made therein without departing from the spirit and scope of theinvention.

1 claim:

A control device of the character described comprising, a normally openelectric switch including a pair 0! cooperating contact members, athermostatic element, a hygrostatic element. and means operable by saidelements conjointly for operating said switch when the relative humidityof the air surrounding said elements falls below a predetermined amountrelative to the temperature of the air, said means including cam membersone associated with each oi! said elements, each oi said cams beingarranged independently to move one of said contact members in responseto operation of its said associated element.

FRANKBUHJOCK.

